CN113117503B - System and method for separating mixed gas by energy-saving hydrate method - Google Patents
System and method for separating mixed gas by energy-saving hydrate method Download PDFInfo
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- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
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- B01D53/78—Liquid phase processes with gas-liquid contact
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
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- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/62—Carbon oxides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/72—Organic compounds not provided for in groups B01D53/48 - B01D53/70, e.g. hydrocarbons
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/96—Regeneration, reactivation or recycling of reactants
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
- C01B3/506—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification at low temperatures
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
- C01B3/52—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with liquids; Regeneration of used liquids
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02C20/00—Capture or disposal of greenhouse gases
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
Abstract
The invention discloses an energy-saving system for separating mixed gas by a hydrate method. The system comprises a compressor, a first heat exchanger, a second heat exchanger, a working liquid cooler, a gas cooler, a hydrate reactor, a solid-liquid separator, a gas-liquid separator, a hydrate decomposer, a clear liquid circulating pump, a working liquid circulating pump, a booster pump and an energy recovery device; the liquid phase outlet of the gas-liquid separator is connected with the high-pressure fluid inlet of the energy recovery device, and the pressure relief fluid outlet of the energy recovery device is connected with the fluid inlet of the hydrate decomposer; the liquid phase outlet of the decomposer is connected with the low-pressure fluid inlet of the energy recovery device through a working fluid circulating pump; the pressurized fluid outlet of the energy recovery device is connected with the liquid phase inlet of the reactor after sequentially passing through the booster pump, the second heat exchanger and the working fluid cooler. The energy recovery device is arranged to recover the pressure energy of the high-pressure hydrate fluid, and the energy recovery device is used for improving the pressure of the hydrate working fluid after gas is decomposed and released, so that the energy consumption for pressurizing the recycled working fluid is reduced.
Description
Technical Field
The invention belongs to the field of gas separation, and relates to a method for separating mixed gas by a hydrate method, in particular to a system and a method for separating mixed gas by an energy-saving hydrate method.
Background
The hydrate technology is a hot point of research at home and abroad in recent years, and besides being used as energy development and utilization, the gas hydrate related technology derives a plurality of new applications for gas storage and transportation, mixed gas and solution separation, sewage treatment, seawater desalination, CO 2 Sealing and cold storage technologies and other fields. In 2014, the 'eighth international natural gas hydrate congress' was held in Beijing, which is held in developing countries for the first time, and shows that the research level of the hydrate in China has gained worldwide approval, and meanwhile, a new round of energy development and related hydrate technology research in China will be caused to be a hot tide. In the application of various hydrate technologies, the mixed gas separation technology is paid much attention by virtue of the advantages of simple flow, mild conditions, flexible operation, greenness, no pollution and the like. The principle of separating the mixed gas by the hydrate technology is that the pressure difference of hydrates formed by different gases is large, and the separation of the components of the mixed gas can be realized by utilizing the pressure difference of the hydrates formed by the different gases and controlling the generation conditions. At present, hydrate separation technology is reported to be applied to the research of gas purification and purification in various fields such as natural gas, flue gas, coal bed gas, synthetic gas, refinery gas, methane and the like.
The separation of the mixed gas by using the hydrate technology requires that the gas with relatively low phase equilibrium pressure forms hydrate by using the pressure difference of hydrate formation of different gases, and the gas with high phase equilibrium pressure does not form hydrate, so as to realize the separation of the mixed gas, but generally, the generation pressure of the gas hydrate is higher, for example, under the condition of the temperature of 273K, the phase equilibrium pressure of some typical gases is as follows: CH (CH) 4 ：2.6MPa、CO 2 ：1.3MPa、O 2 :11.1MPa、N 2 :14.3MPa、H 2 :200MPa, and the phase equilibrium pressure is increased along with the increase of the temperature, and the temperature is 278K，CH 4 With CO 2 The phase equilibrium pressure reaches 4.5MPa and 2.4MPa respectively 2 、N 2 、H 2 The higher the gas phase equilibrium pressure, the greater the energy consumption required to generate the hydrate. In addition, the formed gas hydrate is required to be subjected to decompression and temperature rise release to realize the separation of the mixed gas, and the energy consumption is higher in the continuous gas separation process under the conditions of low temperature and high pressure formed by hydration and high temperature and low pressure released by decomposition, so that the separation is not beneficial to industrial application. At present, in order to reduce the phase equilibrium pressure of the gas hydrate, some macromolecules are added into a hydrate working solution to change the phase equilibrium condition and reduce the hydrate generation temperature and pressure, and the additives become thermodynamic promoters, mainly including Tetrahydrofuran (THF), tetrahydropyran (THP), tetrabutylammonium fluoride (TBAF), cyclopentane (CP), acetone and the like. However, although the thermodynamic promoter can reduce the phase equilibrium pressure of the hydrate, the thermodynamic promoter occupies holes in the hydrate structure, so that the gas storage capacity and the separation effect are limited to a certain extent.
Patent CN105331411A discloses an energy-saving type natural gas hydrate rapid synthesis device and method, wherein high-pressure natural gas is sent to an expansion power generation refrigeration unit for recovering pressure energy of the high-pressure natural gas, the expansion power generation refrigeration unit is cooled for hydrate synthesis refrigeration, the pressure energy recovery of the high-pressure natural gas is realized, and the cold energy is utilized to rapidly synthesize the natural gas hydrate. Patent CN103881775A discloses a coalbed methane hydrate cooling separation and energy recovery device, which reduces production cost by recovering cold in tail gas exhaust gas, cold in unreacted coalbed methane and cold in saturated absorption liquid, but only considers energy recovery in the aspect of heat, and fails to solve the problem of pressure energy consumption in the coalbed methane hydration-decomposition process. Patent CN101456556A discloses CO in mixed gas by hydrate method 2 The industrial separating and purifying system and method includes comprehensive hydrate generating and decomposing heat utilizing system and tail gas energy recovering system, and the comprehensive hydrate generating and decomposing heat and tail gas energy recovering system are utilized in the refrigerating circulation processThe gas compression work and the cold energy are used for the pretreatment of the raw material gas, the energy consumption and the cost in the separation process are low, although the method recovers the gas phase pressure energy and optimizes the heat energy utilization, the liquid phase pressure energy can not be recovered and utilized efficiently, and the whole system still has a large energy consumption reduction space.
In addition, the hydrate is generally in a crystalline form, has poor fluidity and is easy to aggregate and block, and the continuity and large-scale application of the related technology of the hydrate are also restricted. In order to solve the problem of the fluidity of the hydrate, the hydrate is processed into spherical particles and transported by the japan mitsui shipbuilding company, and a dehydration step is required, and the dehydrated hydrate is processed by a pelletizer, which makes the process complicated. Patent CN103030494A, CN101530719A, CN101554560A, CN1762929A and the like adopt a hydrate slurry form, and hydrate and solution which does not react to generate hydrate are circularly conveyed together to solve the fluidity problem, but the mixed slurry needs to be integrally heated when the hydrate is decomposed, and the mixed slurry is integrally cooled after gas is decomposed and released, so that the energy consumption is greatly increased, and the operation cost is increased.
From the analysis, the energy consumption reduction is the research focus of the hydrate method mixed gas separation technology, and has great significance for promoting the industrialization process of the technology. Based on the above, it is necessary to develop an efficient mixed gas separation method which can ensure continuous and stable operation of a separation device and simultaneously fully utilize and couple energy such as heat energy, pressure energy and the like in the process of hydrate generation-decomposition, aiming at the characteristics of a mixed gas separation technology by a hydrate method, so as to reduce operation energy consumption.
Disclosure of Invention
The invention provides an energy-saving system and method for separating mixed gas by a hydrate method, aiming at the problem of high energy consumption in the process of separating mixed gas by the hydrate method, which can effectively recover the pressure energy of high-pressure hydrate fluid, efficiently utilize the cold and heat of reaction fluid, greatly reduce the system energy consumption and save the operating cost.
In order to achieve the above object, the present invention provides, in a first aspect, an energy-saving system for separating a gas mixture by a hydrate method. The system comprises a compressor, a first heat exchanger, a second heat exchanger, a working liquid cooler, a gas cooler, a hydrate reactor, a solid-liquid separator, a gas-liquid separator, a hydrate decomposer, a clear liquid circulating pump, a working liquid circulating pump, a booster pump and an energy recovery device;
the inlet of the compressor is connected with a mixed gas feeding pipeline, and the outlet of the compressor is connected with a gas phase inlet of the first heat exchanger;
the gas phase outlet of the first heat exchanger is connected with the gas phase inlet of the hydrate reactor after passing through the gas cooler; the gas phase outlet of the hydrate reactor is connected with the enriched gas line, and the liquid phase outlet of the hydrate reactor is connected with the inlet of the solid-liquid separator;
the liquid phase outlet of the solid-liquid separator is connected with the liquid phase inlet of the hydrate reactor through a clear liquid circulating pump, and the solid phase outlet of the solid-liquid separator sequentially passes through the first heat exchanger and the second heat exchanger and then is connected with the fluid inlet of the gas-liquid separator;
the gas-liquid separator gas-phase outlet is connected with a gas releasing pipeline, and the gas-liquid separator liquid-phase outlet is connected with the energy recovery device high-pressure fluid inlet; the pressure relief fluid outlet of the energy recovery device is connected with the fluid inlet of the hydrate decomposer;
the gas phase outlet of the hydrate decomposer is connected with a released gas pipeline, and the liquid phase outlet of the decomposer is connected with the low-pressure fluid inlet of the energy recovery device through a working fluid circulating pump;
and a pressurized fluid outlet of the energy recovery device is connected with a liquid phase inlet of the hydrate reactor after sequentially passing through the booster pump, the second heat exchanger and the working fluid cooler.
In the separation system, the hydrate reactor is a device which is beneficial to gas-liquid mass transfer and has a good heat transfer effect, a refrigerant heat taking facility is arranged in the hydrate reactor, the form of the hydrate reactor is not limited, and the hydrate reactor can be one of a stirring type, a spraying type, a bubbling type, a tubular type, a jet type, a supergravity type or an impinging stream type.
In the above separation system, the solid-liquid separator is a continuous solid-liquid separation device, preferably a centrifugal filter.
In the separation system, a pressure control valve is arranged on the gas outlet pipeline of the gas-liquid separator to maintain the pressure in the gas-liquid separator.
In the separation system, the hydrate decomposer is a gas-liquid separation device, is unlimited in form, is internally provided with a heating medium heating facility and is used for supplying heat for hydrate decomposition.
In the above separation system, the energy recovery device is a centrifugal type or positive displacement type energy recovery device, preferably a positive displacement type energy recovery device.
In the above separation system, the energy recovery device preferably has the following structure: the energy recovery device is composed of a pressure energy exchange cylinder, check valve groups and a fluid switching valve group, wherein the pressure energy exchange cylinder is provided with two or more groups, the check valve groups are used for controlling and switching the inlet and outlet of low-pressure fluid and pressurized fluid, the fluid switching valve group is used for controlling and switching the inlet and outlet of high-pressure fluid and pressure relief fluid, and the specific working principle of the check valve groups and the fluid switching valve is explained in a specific implementation mode; the pressure exchange cylinder comprises an outer shell and an inner tube, wherein a low-pressure (pressurization) fluid interface and a high-pressure (pressure relief) fluid interface are respectively arranged at two ends of the outer shell, the inner tube divides the pressure exchange cylinder into an inner cavity and an outer cavity, a sleeve baffle plate is arranged in the outer cavity, the side end of the low-pressure (pressurization) fluid interface of the sleeve baffle plate is closed, a gap channel is reserved between the closed end surface and the side wall end surface of the outer cavity, a gap channel is reserved between the high-pressure (pressure relief) fluid interface side of the sleeve baffle plate and the side wall end surface of the outer cavity, and the arrangement of the sleeve baffle plate enables low-pressure (pressurization) fluid to be in an S path when passing through the outer cavity and finally enter the inner cavity; set up the piston in the inner tube, the piston divides into two chambeies about with interior cavity, prevents to mix between the different feed liquids of both sides, the piston can follow the inner tube and freely remove.
The second aspect of the present invention also provides a method for separating mixed gas by an energy-saving hydrate method, wherein the system described above is applied, and the separation method comprises the following steps:
(1) After being pressurized by a compressor, the mixed gas enters a hydrate reactor after being sequentially treated by a first heat exchanger and a gas cooler and then reacts with a hydrate working solution, components which are easy to generate hydrates in the mixed gas react with the hydrate working solution and enter a hydrate phase to form hydrate slurry, and components which are difficult to generate hydrates are enriched in a gas phase and discharged out of the hydrate reactor;
(2) Enabling the hydrate slurry obtained in the step (1) to enter a solid-liquid separator, separating the hydrate slurry into cold clear liquid and a hydrate-rich phase after separation treatment, returning the cold clear liquid to the reactor, enabling the hydrate-rich phase to enter a gas-liquid separator after heat exchange and temperature rise of a first heat exchanger and a second heat exchanger in turn, discharging a gas phase in the gas-liquid separator, and enabling a liquid-phase high-pressure fluid to enter an energy recovery device;
(3) In the energy recovery device, the liquid-phase high-pressure fluid in the step (2) is subjected to pressure energy exchange with the low-pressure working fluid discharged by the hydrate decomposer, the low-pressure working fluid is pressurized into high-pressure working fluid, meanwhile, the high-pressure fluid is depressurized into low-pressure fluid, the high-pressure working fluid is further pressurized by the booster pump, then sequentially subjected to cooling treatment by the second heat exchanger and the working fluid cooler and then enters the hydrate reactor, and the depressurized low-pressure fluid enters the hydrate decomposer;
(4) And (3) decomposing the low-pressure fluid hydrate in the step (3) in a hydrate decomposer to release high-concentration absorbed gas, discharging the gas out of the decomposer, simultaneously enabling the obtained regenerated hydrate working solution to enter an energy recovery device through a circulating pump, and returning the pressurized regenerated hydrate working solution to a hydrate reactor for recycling.
In the above mixed gas separation method, the operating conditions of the hydrate reactor in step (1) are as follows: the temperature is 0-10 ℃, the pressure is 2 MPa-10 MPa, and the specific operation conditions need to be determined according to the treated mixed gas system.
In the above mixed gas separation method, in the hydration reactor in step (1), the hydrate slurry refers to a mixed solution of a formed hydrate and an unreacted hydrate working solution, and the volume fraction of the hydrate formed by the reaction in the hydrate slurry is 20-90%, preferably 30-70%.
In the mixed gas separation method, the temperature of the mixed gas in the step (1) is matched with the operation temperature of the hydrate reactor after the mixed gas is treated by the first heat exchanger and the gas cooler.
In the above mixed gas separation method, the hydrate working solution in step (1) may be an aqueous solution, or may be added with various accelerators, such as one or more of kinetic accelerators including Sodium Dodecyl Sulfate (SDS), sodium Dodecyl Benzene Sulfonate (SDBS), linear sodium alkylsulfonate (LAB-SA), alkyl Polyglycoside (APG), and the like, or thermodynamic accelerators including Tetrahydrofuran (THF), tetrahydropyran (THP), tetrabutylammonium bromide (TBAB), tetrabutylammonium fluoride (TBAF), cyclopentane (CP), acetone, and the like.
In the above mixed gas separation method, the solid-liquid separator in the step (2) is a continuous solid-liquid separation device, preferably a centrifugal filter, and the separation conditions are the same as those of the hydrate reactor.
In the above mixed gas separation method, the gas-liquid separator in step (2) is a high-pressure gas-liquid separator for gas-liquid separation of the rich hydrate decomposed after heating, the operating pressure is the same as that of the hydrate reactor, and the pressure is maintained by discharging the gas through a pressure control valve on the gas outlet line.
In the above mixed gas separation method, the energy recovery device in step (3) is a centrifugal or positive displacement type energy recovery device, preferably a piston type positive displacement energy recovery device, to avoid the mixing of high and low pressure fluids, the positive displacement type energy recovery device adopts a positive displacement working principle, and has a very high energy recovery efficiency through the conversion of pressure energy-pressure energy, and the pressure energy recovery can reach more than 90%.
In the above mixed gas separation method, the piston-type positive displacement energy recovery device in step (3) preferably has the following structure: the energy recovery device is composed of a pressure energy exchange cylinder, check valve groups and a fluid switching valve group, wherein the pressure energy exchange cylinder is provided with two or more groups, the check valve groups are used for controlling and switching the inlet and outlet of low-pressure fluid and pressurized fluid, the fluid switching valve group is used for controlling and switching the inlet and outlet of high-pressure fluid and pressure relief fluid, and the specific working principle of the check valve groups and the fluid switching valve is explained in a specific implementation mode; the pressure exchange cylinder comprises an outer shell and an inner tube, wherein a low-pressure (pressurization) fluid interface and a high-pressure (pressure relief) fluid interface are respectively arranged at two ends of the outer shell, the inner tube divides the pressure exchange cylinder into an inner cavity and an outer cavity, a sleeve baffle plate is arranged in the outer cavity, the side end of the low-pressure (pressurization) fluid interface of the sleeve baffle plate is closed, a gap channel is reserved between the closed end surface and the side wall end surface of the outer cavity, a gap channel is reserved between the high-pressure (pressure relief) fluid interface side of the sleeve baffle plate and the side wall end surface of the outer cavity, and the sleeve baffle plate is arranged to enable low-pressure (pressurization) fluid to be in an S path when passing through the outer cavity and finally enter the inner cavity; set up the piston in the inner tube, the piston divides into two chambeies about with interior cavity, prevents to mix between the different feed liquids of both sides, the piston can follow the inner tube and freely remove.
In the energy recovery device, during operation, the pressure energy exchange cylinder can realize pressure energy exchange between high-pressure fluid discharged by the hydrate reactor and low-pressure working fluid discharged by the hydrate decomposer, so that the low-pressure working fluid is converted into the high-pressure working fluid by pressurization, and meanwhile, the hydrate high-pressure fluid is converted into the low-pressure fluid by depressurization.
In the energy recovery device, when in operation, the low-pressure (pressurization) fluid and the high-pressure (pressure relief) fluid carry out certain heat transfer through the inner pipe wall, so that the wall climbing phenomenon of the inner cavity hydrate-rich cold fluid on the inner pipe wall is prevented.
In the mixed gas separation method, the pressurized working fluid in the step (3) is treated by the second heat exchanger and the working fluid cooler and then cooled to match with the operating temperature of the hydrate reactor.
In the mixed gas separation method, the fluid pressure of the pressurized working fluid processed by the booster pump in the step (3) is matched with the pressure of the hydrate reactor.
In the mixed gas separation method, the pressure of the low-pressure fluid after pressure reduction in the step (3) is matched with the pressure of the hydrate decomposer.
In the above mixed gas separation method, the operating conditions of the hydrate decomposer in the step (4) are as follows: the pressure is 0.1MPa to 2.0MPa, and the decomposition temperature is 10 ℃ to 50 ℃.
The system and the method for separating the mixed gas by the energy-saving hydrate method can be applied to natural gas (CH) 4 /CO 2 ) Purification and biogas (CH) 4 /CO 2 ) Purification, gas decarburization (N) 2 /CO 2 ) Coal bed methane separation (CH) 4 /N 2 /O 2 ) Decarbonization of synthesis gas (CO) 2 /H 2 ) And light hydrocarbon recovery (light hydrocarbon/H) from refinery gas 2 ) Processing, and the like.
Compared with the prior art, the system and the method for separating the mixed gas by the energy-saving hydrate method have the following advantages:
1. aiming at the difference of two working procedure operation conditions of gas formation hydrate and hydrate decomposition in the process of separating mixed gas by a hydrate method, the pressure energy of high-pressure hydrate fluid is recovered by an energy recovery device, the pressure energy is used for improving the pressure of hydrate working fluid after gas is decomposed and released, the pressure energy of reaction fluid is efficiently utilized, the recovery efficiency can reach more than 90 percent, and the energy consumption required for pressurizing the recycling of regeneration working fluid is greatly reduced.
2. Hydrate generation is carried out in a hydrate slurry form, the mobility of the hydrate is maintained, and the hydrate slurry is divided into a hydrate-rich crystalline phase and a cold clear liquid phase through solid-liquid separation equipment: the hydrate content in the cold clear liquid phase is extremely low, the temperature does not need to be raised, and the lower temperature can be maintained for recycling; the hydrate-rich crystal phase enters a gas-liquid separator after exchanging heat with high-temperature air inlet and high-temperature regeneration circulating working solution, the heated hydrate-rich crystal phase is partially decomposed and is changed into a slurry form with better fluidity again, the fluidity is better, the cold energy of low-temperature hydrate fluid is recycled at the same time, the fluid entering a reactor is precooled, the cold and heat in the treatment process are fully utilized, the system energy consumption is greatly reduced, and the operating cost is saved.
3. According to the optimized energy recovery device provided by the invention, through the structural design of the inner cavity and the outer cavity, the high-temperature and low-pressure regeneration working solution and the low-temperature and high-pressure hydrate fluid realize pressure energy exchange, and simultaneously, heat exchange is carried out through the inner tube wall, so that the wall climbing phenomenon of the hydrate-rich cold fluid in the inner cavity on the inner tube wall surface is avoided, the smooth movement of a piston of the inner cavity is maintained, and the normal operation of a pressure energy exchange cylinder is ensured.
Drawings
FIG. 1 is a schematic diagram of a system for separating a mixed gas by an energy-saving hydrate method.
In the figure, 1-mixed gas, 2-compressor, 3-first heat exchanger, 4-hydrate reactor, 5-enriched gas line, 6-working fluid cooler, 7-gas cooler, 8-second heat exchanger, 9-hydrate decomposer, 10-decomposed gas line, 11-energy recovery device, 12-booster pump, 13-working fluid circulating pump, 14-hydrate slurry stream, 15-pressure relief fluid, 16-regenerated low-pressure working fluid, 17-regenerated booster working fluid, 18-low-pressure fluid inlet line, 19-hydrate-enriched crystalline stream, 20-cold clear liquid stream, 21-clear liquid circulating pump, 22-gas-liquid separator, 23-high-pressure fluid, 24-pressure control valve, 25-solid-liquid separator.
Fig. 2 is a schematic diagram of the structure and principle of the energy recovery device of the present invention.
In the figure, 51-check valve group, 52-fluid switching valve group, 53-pressure energy exchange cylinder a, 54-pressure energy exchange cylinder B, 56-pressurized fluid, 57-low pressure fluid, 58-high pressure fluid, 59-pressure relief fluid.
Fig. 3 is a schematic structural diagram of a pressure energy exchange cylinder in the energy recovery device of the invention.
In the figure, 81-outer shell, 82-inner tube, 83-sleeve baffle, 84-piston, 85-outer cavity, 86-inner cavity, 87-limiting component, 88-low pressure (pressurization) fluid interface, and 89-high pressure (decompression) fluid interface.
Fig. 4 is a schematic view of a straight pipe piston type positive displacement energy recovery device in embodiment 1.
Detailed Description
The following detailed description of the system and method for separating mixed gas by energy-saving hydrate method according to the present invention will be made with reference to the accompanying drawings and examples, but the present invention is not limited thereto.
As shown in fig. 1, the invention provides an energy-saving hybrid gas separation system by a hydrate method, which comprises a compressor 2, a first heat exchanger 3, a second heat exchanger 8, a working fluid cooler 6, a gas cooler 7, a hydrate reactor 4, a solid-liquid separator 25, a gas-liquid separator 22, a hydrate decomposer 9, a clear liquid circulating pump 21, a working fluid circulating pump 13, a booster pump 12 and an energy recovery device 11. The inlet of the compressor 2 is connected with the mixed gas feeding pipeline 1, and the outlet of the compressor 2 is connected with the gas phase inlet of the first heat exchanger 3; the gas phase outlet of the first heat exchanger 3 is connected with the gas phase inlet of the hydrate reactor 4 after passing through the gas cooler 7; the gas phase outlet of the hydrate reactor 4 is connected with the enriched gas pipeline 5, and the liquid phase outlet of the hydrate reactor 4 is connected with the inlet of the solid-liquid separator 25; the liquid phase outlet 20 of the solid-liquid separator is connected with the liquid phase inlet of the hydrate reactor 4 through a clear liquid circulating pump 21, and the solid phase outlet 19 of the solid-liquid separator is connected with the fluid inlet of the gas-liquid separator 22 after sequentially passing through the first heat exchanger 3 and the second heat exchanger 8; the gas-liquid separator 22 gas-phase outlet is connected with the gas releasing pipeline 10 through a pressure control valve 24, and the gas-liquid separator 22 liquid-phase outlet is connected with the energy recovery device high-pressure fluid inlet 23; the pressure relief fluid outlet 15 of the energy recovery device is connected with the fluid inlet of the hydrate decomposer 9; the gas phase outlet of the hydrate decomposer 9 is connected with a released gas pipeline 10, and the liquid phase outlet 16 of the decomposer is connected with the low-pressure fluid inlet 18 of the energy recovery device through a working fluid circulating pump 13; and a pressurized fluid outlet 17 of the energy recovery device is connected with a liquid phase inlet of the hydrate reactor 4 after sequentially passing through a booster pump 12, a second heat exchanger 8 and a working fluid cooler 6.
As shown in fig. 2, the structure and the working principle of the energy recovery device of the present invention are as follows: the energy recovery device comprises two or more groups of pressure energy exchange cylinders (two groups of structures are selected in fig. 2, namely a pressure energy exchange cylinder A53 and a pressure energy exchange cylinder B54), a check valve group 51 and a fluid switching valve group 52. The high-pressure hydrate fluid 58 enters the pressure energy exchange cylinder A53 through the fluid switching valve group 52, transfers pressure energy to low-pressure working fluid which is filled in the exchange cylinder A53 previously, and drives the pressurized working fluid to be discharged through the check valve group 51, which is a pressurization process; at the same time, low pressure working fluid 57 enters pressure energy exchange cylinder B54 through check valve set 51, driving relief hydrate fluid 59 out through fluid switching valve set 52, which is the relief process. After the working stroke in the two pressure energy exchange cylinders is completed, the two pressure energy exchange cylinders are switched through the fluid switching valve group 52, and the working stroke is exchanged. The processes of pressurization and pressure relief are regularly and alternately carried out in the two pressure energy exchange cylinders, so that the energy exchange of the high-pressure hydrate fluid 58 and the low-pressure working fluid 57 is realized, and the continuous and stable operation of the energy recovery device is ensured.
As shown in fig. 3, in the energy recovery device according to the system and method of the present invention, the pressure energy exchange cylinder includes an outer shell 81 and an inner tube 82, two ends of the outer shell 81 are respectively provided with a low pressure (pressurization) fluid interface 88 and a high pressure (pressure release) fluid interface 89, the inner tube 82 divides the pressure exchange cylinder into an inner cavity 86 and an outer cavity 85, a sleeve baffle 83 is disposed in the outer cavity 85, the low pressure (pressurization) fluid interface side end of the sleeve baffle is closed, a gap channel is left between the closed end surface and the outer cavity side wall end surface, a gap channel is left between the high pressure (pressure release) fluid interface side of the sleeve baffle and the outer cavity side wall end surface, and the arrangement of the sleeve baffle 83 makes the low pressure (pressurization) fluid to be an "S" path when passing through the outer cavity 85, and finally enter the inner cavity 86; set up piston 84 in the inner tube 82, the piston divides into two chambeies about with interior cavity, prevents to mix between the different feed liquids of both sides, piston 84 can follow inner tube 82 and freely move.
With reference to fig. 1, 2 and 3, the working process of separating the mixed gas by the mixed gas separation system and method provided by the invention is as follows: after being pressurized by a compressor 2, the mixed gas 1 to be treated sequentially passes through a first heat exchanger 3 and a gas cooler 7 and then enters a hydrate reactor 4 to react with a hydrate working solution, components which are easy to generate hydrates in the mixed gas react with the hydrate working solution and enter hydrate phases to form hydrate slurry, components which are difficult to generate hydrates are enriched in a gas phase, and the components are discharged from the hydrate reactor 4 and enter an enrichment gas line 5; the hydrate slurry enters a solid-liquid separator 25, is separated into cold clear liquid and a hydrate-rich phase after separation treatment, the cold clear liquid 20 returns to the reactor, the hydrate-rich phase 19 enters a gas-liquid separator 22 after heat exchange and temperature rise through a first heat exchanger 3 and a second heat exchanger 8 in sequence, the gas phase in the gas-liquid separator is discharged, and the liquid-phase high-pressure fluid enters an energy recovery device 11; in the energy recovery device, high-pressure fluid and low-pressure working fluid discharged by a hydrate decomposer 9 are subjected to pressure energy exchange, the low-pressure working fluid is pressurized into high-pressure working fluid, the high-pressure fluid is depressurized into low-pressure fluid, the high-pressure working fluid 17 is further pressurized by a booster pump 12, then sequentially passes through a second heat exchanger 8 and a working fluid cooler 6 to be subjected to temperature reduction treatment, then enters a hydrate reactor 4, the depressurized low-pressure fluid 15 enters the hydrate decomposer 9, high-concentration absorbed gas is discharged in the hydrate decomposition 9 and discharged out of the decomposer to enter a decomposition gas pipeline 10, and meanwhile, the obtained regenerated hydrate working fluid enters an energy recovery device 11 through a circulating pump 13 and returns to the hydrate reactor 4 for recycling after pressurization.
Example 1
The system shown in fig. 1 and the pressure energy recovery device shown in fig. 4 are adopted to perform hydrogen concentration treatment on refinery gas. Refinery gas composition: h 2 Volume content 40%, CH 4 25% of volume content, the rest is light hydrocarbon and a small amount of CO 2 And the like. The hydrate working solution is TBAB containing 4% of mass fraction and SDS aqueous solution of 300 mg/kg.
The refinery gas enters a hydrate reactor after being pressurized, and the conditions of the hydrate reactor are as follows: pressure 7.0MPa, temperature 5 deg.C, CH in refinery gas 4 Light hydrocarbon and CO 2 The gas reacts with the hydrate working fluid to enter the hydrate phase to form hydrate slurry, H 2 The components are not easy to generate hydrate and are enriched in gas phase, the generation amount of the hydrate is controlled by about 50% of the total volume amount of hydrate slurry through reaction, the mixed gas is discharged out of a hydrate reactor after being processed, and H in the gas 2 The content is higher than 80%; introducing the hydrate slurry into a solid-liquid separator to obtain a cold clear liquid and a hydrate-rich crystalline phase, wherein the mass content of the hydrate in the cold clear liquid is less than 10%, the cold clear liquid enters a reactor for circulation, the temperature of the hydrate-rich crystalline phase is raised by a first heat exchanger and a second heat exchanger and then enters a gas-liquid separator, the gas-liquid separator maintains the pressure of about 6.5MPa, the gas is discharged from the separator, the hydrate slurry with the pressure of 6.5MPa enters an energy recovery device and is subjected to pressure energy exchange with low-pressure working fluid discharged by a hydrate decomposer, the low-pressure working fluid is pressurized from 0.4MPa to 6.3MPa, and meanwhile, the low-pressure fluid with the pressure of 0.2MPa reduced by the hydrate slurry enters the hydrate decomposer; hydrate decomposer condition 0.2MPaAt a temperature of 25 ℃, under which conditions the hydrate fluid decomposes to release H-depleted gas 2 And (4) tail gas. By the process, H in refinery gas is treated 2 Concentrating and recovering to obtain rich H 2 H in gas 2 Content higher than 80%, H 2 The recovery rate is higher than 85 percent. The good mobility of hydrate in the device can be guaranteed to whole processing procedure to greatly reduced the process energy consumption: the hydrate slurry is processed by the solid-liquid separator, and only the hydrate-rich crystals are regenerated, so that the energy consumption for dissolving the hydrate is reduced by more than 30%; the pressure energy of the high-pressure fluid is efficiently recycled, and more than 90% of the pressure energy of the high-pressure hydrate fluid is recycled; in addition, the system also optimizes the conversion between cold energy and hot energy, the comprehensive energy consumption of the whole process is reduced by about 20 percent compared with the comprehensive energy consumption of the separation treatment of the mixed gas by the traditional hydrate method, and the energy conservation and the consumption reduction are fully realized.
In this embodiment, by using the conventional positive displacement energy recovery device, during the process of converting pressure energy of low-temperature hydrate fluid, the risk of hydrate wall climbing due to crystallization on the inner wall of the pipe may occur, which may result in the situation that the piston cannot move smoothly, thereby affecting the normal operation of the pressure energy exchange cylinder, and the energy recovery device cannot guarantee continuous and stable operation.
Example 2
The method for separating the mixed gas by the hydrate method is shown in figure 1, and the energy recovery device shown in figures 2 and 3 is selected to carry out hydrogen concentration treatment on the refinery gas, and the rest is the same as the embodiment 1. Because the energy recovery device shown in fig. 2 and 3 is adopted to recover the pressure energy of the high-pressure hydrate fluid, aiming at the characteristic that the hydrate in the high-pressure fluid is easy to crystallize, through the structural design of the inner cavity and the outer cavity, the high-temperature and low-pressure regeneration working fluid exchanges the pressure energy with the low-temperature and high-pressure hydrate fluid, and simultaneously, the heat exchange is carried out through the inner pipe wall, so that the inner cavity hydrate-rich cold fluid has certain temperature rise at the inner pipe wall, the wall climbing phenomenon of the hydrate in the process of pressure energy conversion is avoided, the smooth movement of the piston can be ensured, and the stable operation of the energy recovery device can be maintained.
Comparative example 1
The same as in example 1, except that no energy recovery device was provided. Because no energy recovery device is arranged, the whole system needs to pressurize the working fluid to 7.0MPa for hydration reaction in the continuous separation treatment process of the mixed gas, the pressure of the gas is reduced to 0.2MPa after the gas forms a hydrate, so that the hydrate is decomposed to release the gas, and then the regenerated working fluid is pressurized from 0.2MPa to 7.0MPa for recycling.
Claims (14)
1. An energy-saving system for separating mixed gas by a hydrate method comprises a compressor, a first heat exchanger, a second heat exchanger, a working liquid cooler, a gas cooler, a hydrate reactor, a solid-liquid separator, a gas-liquid separator, a hydrate decomposer, a clear liquid circulating pump, a working liquid circulating pump, a booster pump and an energy recovery device; the inlet of the compressor is connected with a mixed gas feeding pipeline, and the outlet of the compressor is connected with a gas phase inlet of the first heat exchanger;
the gas phase outlet of the first heat exchanger is connected with the gas phase inlet of the hydrate reactor after passing through the gas cooler; the gas phase outlet of the hydrate reactor is connected with the enriched gas line, and the liquid phase outlet of the hydrate reactor is connected with the inlet of the solid-liquid separator;
the liquid phase outlet of the solid-liquid separator is connected with the liquid phase inlet of the hydrate reactor through a clear liquid circulating pump, and the solid phase outlet of the solid-liquid separator sequentially passes through the first heat exchanger and the second heat exchanger and then is connected with the fluid inlet of the gas-liquid separator;
the gas-liquid separator gas-phase outlet is connected with a gas releasing pipeline, and the gas-liquid separator liquid-phase outlet is connected with the energy recovery device high-pressure fluid inlet; the pressure relief fluid outlet of the energy recovery device is connected with the fluid inlet of the hydrate decomposer;
the gas phase outlet of the hydrate decomposer is connected with a released gas pipeline, and the liquid phase outlet of the decomposer is connected with the low-pressure fluid inlet of the energy recovery device through a working fluid circulating pump;
the pressurized fluid outlet of the energy recovery device is connected with the liquid phase inlet of the hydrate reactor after sequentially passing through the booster pump, the second heat exchanger and the working fluid cooler;
the energy recovery device consists of pressure energy exchange cylinders, check valve groups and fluid switching valve groups, wherein more than two groups of pressure energy exchange cylinders are arranged; the check valve group is used for controlling and switching the inlet and outlet of low-pressure fluid and pressurized fluid, and the fluid switching valve group is used for controlling and switching the inlet and outlet of high-pressure fluid and pressure relief fluid; the pressure energy exchange cylinder comprises an outer shell and an inner tube, and a low-pressure fluid interface and a high-pressure fluid interface are respectively arranged at two ends of the outer shell; the pressure energy exchange cylinder is divided into an inner cavity and an outer cavity by the inner tube, a sleeve baffle plate is arranged in the outer cavity, the low-pressure fluid interface side end of the sleeve baffle plate is closed, a gap channel is reserved between the closed end surface and the side wall end surface of the outer cavity, and a gap channel is reserved between the high-pressure fluid interface side of the sleeve baffle plate and the side wall end surface of the outer cavity; the inner tube is internally provided with a piston, the piston divides the inner cavity into a left cavity and a right cavity, and the piston can freely move along the inner tube.
2. The system of claim 1, wherein the hydrate reactor is internally provided with a coolant heat extraction facility.
3. The system of claim 1, wherein the hydrate reactor is one of an agitated, sparged, bubbled, tubular, jet, hypergravity, or impinging flow reactor.
4. The system of claim 1, wherein the solid liquid separator is a centrifugal filter.
5. The system of claim 1, wherein a pressure control valve is disposed in the gas outlet line of the gas-liquid separator to maintain pressure in the gas-liquid separator.
6. The system according to claim 1, wherein a heating medium heating facility is arranged inside the hydrate decomposer and is used for supplying heat for hydrate decomposition.
7. The system of claim 1, wherein the energy recovery device is a positive displacement energy recovery device.
8. An energy-saving hydrate method for separating mixed gas, wherein the system of any one of claims 1-7 is applied, and the method for separating the mixed gas comprises the following steps:
(1) After being pressurized by a compressor, the mixed gas enters a hydrate reactor after being sequentially treated by a first heat exchanger and a gas cooler and then reacts with a hydrate working solution, components which are easy to generate hydrates in the mixed gas react with the hydrate working solution and enter a hydrate phase to form hydrate slurry, and components which are difficult to generate hydrates are enriched in a gas phase and discharged out of the hydrate reactor;
(2) Enabling the hydrate slurry obtained in the step (1) to enter a solid-liquid separator, separating the hydrate slurry into cold clear liquid and a hydrate-rich phase, returning the cold clear liquid to the reactor, enabling the hydrate-rich phase to enter a gas-liquid separator after heat exchange and temperature rise of a first heat exchanger and a second heat exchanger in turn, discharging a gas phase in the gas-liquid separator, and enabling a liquid-phase high-pressure fluid to enter an energy recovery device;
(3) In an energy recovery device, the liquid-phase high-pressure fluid in the step (2) and the low-pressure working fluid discharged by the hydrate decomposer are subjected to pressure energy exchange, the low-pressure working fluid is pressurized into high-pressure working fluid, meanwhile, the high-pressure fluid is depressurized into low-pressure fluid, the high-pressure working fluid is further pressurized by a booster pump, then sequentially subjected to cooling treatment by a second heat exchanger and a working fluid cooler and then enters a hydrate reactor, and the depressurized low-pressure fluid enters the hydrate decomposer;
(4) And (3) decomposing the low-pressure fluid hydrate in the step (3) in a hydrate decomposer to release high-concentration absorbed gas, discharging the gas out of the decomposer, simultaneously enabling the obtained regenerated hydrate working solution to enter an energy recovery device through a circulating pump, and returning the pressurized regenerated hydrate working solution to a hydrate reactor for recycling.
9. The method of claim 8, wherein the operating conditions of the hydrate reactor are: the temperature is 0-10 ℃, and the pressure is 2 MPa-10 MPa.
10. The method of claim 8, wherein the hydrate slurry of step (1) has a volume fraction of 20% to 90% of hydrate produced by the reaction.
11. The method of claim 8, wherein the hydrate working fluid is an aqueous solution.
12. The method according to claim 8 or 11, wherein an accelerator is added into the hydrate working solution, and the accelerator is selected from one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, linear sodium alkyl sulfonate, alkyl polyglycoside, tetrahydrofuran, tetrahydropyran, tetrabutylammonium bromide, tetrabutylammonium fluoride, cyclopentane and acetone.
13. The process of claim 8, wherein the gas-liquid separator of step (2) is operated at the same pressure as the hydrate reactor.
14. The method of claim 10, wherein the hydrate slurry of step (1) has a volume fraction of 30% to 70% hydrate.
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Effective date of registration: 20231114 Address after: 100728 No. 22 North Main Street, Chaoyang District, Beijing, Chaoyangmen Patentee after: CHINA PETROLEUM & CHEMICAL Corp. Patentee after: Sinopec (Dalian) Petrochemical Research Institute Co.,Ltd. Address before: 100728 No. 22 North Main Street, Chaoyang District, Beijing, Chaoyangmen Patentee before: CHINA PETROLEUM & CHEMICAL Corp. Patentee before: DALIAN RESEARCH INSTITUTE OF PETROLEUM AND PETROCHEMICALS, SINOPEC Corp. |
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